This invention relates to food snack products and more particularly to a novel fried snack chip having a bubbled surface, with the extent of bubbling being controlled by process parameters.
Chip products (whether they be potato chips, corn or tortilla chips, etc.) are typically prepared by frying either thin slices of raw, fresh potatoes or individual chip-sized pieces of a dough made from the raw material. Such products have become increasingly popular among consumers, who are demanding an ever increasing variety of novel shapes, flavors, textures, etc.
While "potato chips" were for many years limited to fried slices of raw potatoes, increasingly the term may be inclusive of "fabricated" products as well, as evidenced by Pringles brand potato snacks manufactured by the Proctor & Gamble Company, Tato Skins brand potato snacks manufactured by the Keebler Co. Generally speaking, most prior art fabricated potato chips relied for their textural qualities upon the internal expansion of a potato-based dough to achieve the crispness and mouth feel consumers associate with conventional potato chips. Generally speaking, most prior art expanded potato snacks (i.e., snacks produced from a potato-based dough which is expanded to a porous condition by immersion in hot cooking oil) have not successfully duplicated the appearance and/or texture of potato chips because they have not duplicated the bubbling found on all conventional potato chips.
As used herein, the following words have the following definitions:
"Bubbles" or "bubbling"--separation of portions of either or both of the upper or lower surface portions of the dough preform into a number of rounded areas which protrude from the surface of the fried snack, the surface or wall of the bubble having a thinner cross-sectional dimension than that of an unbubbled portion of the fried snack.
"Pillowing"--the uncontrolled separation of a major portion of the upper and lower surface portions of a dough preform to give a rounded pillow-like area on the fried product, having extremely thin cross-sectional dimension, usually resulting in breakage.
"Blister" or "blistering"--similar to a pillow except that a blister may protrude from a single surface of the fried product, rather than both surfaces, although it will typically be broken like a pillow.
"Expanded"--refers to the internal texture of many sheeted or extruded snack products, wherein a large number of small bubbles are formed between the upper and lower surfaces of the snack product. In some expanded products, the bubbles may extend above the surface of the snack, but because they appear in such large numbers, they become the outer surface of the snack. Such products would not be considered "bubbled" or "blistered" within the context of this invention.
Blisters and pillows form in conventional potato chips because during frying of the potato slice, the starch in the outer cell layers gels and becomes dehydrated more rapidly than that starch in the center of the potato slice. Expanding steam is thus trapped within the intercellular spaces of the potato slice, forcing the cells apart as the middle lamella pectic substances between adjacent cell walls become softened and solublized. Microscopic Structure of Potato Chips, R. M. Reeve and E. M. Neel, American Potato Journal, Vol. 37 p.48. Typically, control of such blistering in fabricated potato chips is a function of dough moisture: as the moisture increases, blistering increases, and as moisture decreases, blistering decreases due to the lesser availability of water to make the entrapped steam. Excess Blistering is undesirable because chips break too readily and because they may contain large amounts of oil (American Potato Journal, Vo. 37). Such undesirable blistering and pillowing is controlled by lowering the dough moisture, even though such relatively dry dough is more difficult to handle during a sheeting process. Coincidentally, the lower dough moisture typically results in lower fat contents in the finished product, a phenomenon well-known to all those skilled in the art.
Corn and tortilla chips produced either by extrusion or sheeting processes, produce end products having relatively little pillowing or blistering, and a relatively unexpanded texture. The lack of bubbles in such products is due either to the presence of relatively coarse particulate materials (which provide "vents" for the escape of internally generated steam) or the process utilized to make the products. When extruded, low-moisture doughs are utilized. When sheeted, higher-moisture doughs are used, but prior to frying the individual dough preforms are baked in an oven for about 15-30 seconds at a temperature of about 302.degree.-316.degree. C. (575.degree.-600.degree. F.) in order to reduce the dough moisture. However, when making fried tortilla chips, after baking the dough preforms are equilibrated for a few minutes prior to frying. The equilibration produces uniform distribution of water within the dough preform, thereby reducing blisters and oil absorption during frying. (Corn: Chemistry and Technology, Watson, Ramstad, Editors).
The problem of excess bubbling or pillowing in sheeted, fried corn chips has been observed in U.S. Pat. No. 2,905,559, wherein sheeted masa dough is perforated with sharply pointed spikes, the perforations being from one-half to one-eighth inch apart. The resulting product is free from entrapped voids throughout, and all pillowing was eliminated. Likewise, pillowing of pizza dough during baking is a problem dealt with in U.S. Pat. Nos. 4,170,659 and 4,395,216. In the '659 patent, pizza dough is dockered using pins having diameters of from 3/32 inch to about 1/4 inch and spaced about one inch apart. While the dockering holes will prevent the total pillowing of the pizza dough sheet, the dough is intended to pillow somewhat between the dockering holes. In '216, a pizza dough sheet is perforated using a star wheel, in which the point of the star wheel protrudes through the dough sheet and against a backup member. U.S. Pat. No. 3,880,069 discloses a perforating roll in which a pizza dough sheet is perforated by spikes, presumably to reduce or eliminate pillowing, and U.S. Pat. No. 3,278,311 discloses a corn dough sheet perforated by a dockering roll, presumably to eliminate undesirable pillowing. Finally, U.S. Pat. No. 4,650,687, commonly owned by the applicant herein, discloses a dockering process whereby blistering or pillowing is eliminated in a sheeted dough by the use of a dockering brush comprising flexible bristles which protrude through the dough sheet and against a backup member.
Various other methods of reducing blistering have been proposed in the art. For instance, the surface of a dough having a moisture content of about 25-50 percent is moistened by spraying with water, dipping in water or by steaming, so that when fried, blisters or pillows are eliminated. (U.S. Pat. No. 3,883,671) U.S. Pat. Nos. 3,493,390 and 3,519,432 disclose processes for forming a fabricated potato chip having a blistered surface resembling that of conventional potato chips. In the '432 patent, a sheeted potato dough is baked either in a 1- or a 2-phase process for from 4-16 minutes, in order to obtain the desired blistered surface. Likewise, the '390 patent provides that a chip may be prepared by laminating two or more frozen dough wafers, the air between adjacent wafers expanding upon heating and forming blisters between the wafers. Alternatively, frozen moisture on the surface of the wafers forms steam upon heating thereby causing the wafers to separate and form surface blisters. A final method whereby blistering or pillowing is prevented is by the formation of "pellets" or dried half-products. By removing substantially all of the water from a dough piece by drying, subsequent "puffing" either by frying, hot air or otherwise, will result in a greatly expanded, puffed product with little or no surface blistering, since very little water was present in the fried half-product. Examples of such technology include U.S. Pat. Nos. 3,690,895, 3,502,479, 3,230,094 and 3,800,050.